There are a great many inventions in the past that use the burning fuel with oxygen in the presence of water, all under pressure. Steam has been produced in this manner for over 100 years to produce a pressurized working fluid for an engine. Some of the earliest inventions are torpedoes which utilize this type of a power plant. The burning of the fuel in the presence of water is an easy way to derive steam under pressure. In almost all of the inventions the constant pressure method is used whereby the fluid is sent to the engine expansion chamber under an almost constant pressure. Then the steam is discharged from the expansion chamber to the atmosphere or is recovered in the form of water by a cooling system. The heat in the exhaust steam is mostly lost in past inventions. Therefore, the water recovered had to be reheated by new fuel in the combustion chamber, which is very costly.
There is another type of invention that is related to the above type invention. This type of invention utilizes an external combustion chamber to heat air with a small amount of water for the production of hot gasses. One of the earliest external combustion engines made no mention of water or steam, and so it was concerned mainly with heating the air accompanying the oxygen. Of course there is always some water vapor in air. Some of the more recent engines utilize a water spray in the air compression chamber, mainly to keep the temperature down. Here the generation of steam is used to keep the engine from burning up. It is well known that temperatures as high as 4000.degree. Fahrenheit are present in an internal combustion engine. These high temperatures are not feasible for external combustion chambers where the fluid is maintained at a constant pressure and temperature. Therefore, water injection is used in more recent inventions in both the air compression cyclinder and the combustion chamber.
In searching the prior art little or nothing was found in the art of turning steam back into steam. There are inventions that produce steam from the exhausts of gas turbines, this steam being used to run a steam turbine. It has been generally accepted that it is uneconomical to try to recompress steam to be used again because the recompression cycle takes as much or more energy than the expansion cycle. Thus, no work would be done. Also, in searching the prior art, there was nothing found about an invention that utilizes a variable pressure steam external combustion chamber. It is true that all combustion chambers experience a fluctuation in pressure. However, the principal of the variable pressure steam external combustion chamber has never been invented or explored, to the knowledge of the inventor. It is well known that the internal combustion chamber must work on the variable pressure motif, and so must the external combustion chamber, if it is combined in some way with the internal chamber or cylinder.